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doi: 10.1111/j.1151-2916.1921.tb17331.xpmid: N/A
ABSTRACT Effect of heating Japanese kaolinite at 100° to 1400° C for 3 to 4 hours.—Ignition loss of weight Was found to occur chiefly between 400° and 600°C, the rate of increase per degree reaching a maximum at about 460 °C. Changes of microstructure were observed at 600°, 900–1000°, 1250–1300° and at 1400 °C, when sillimanite began to develop. Heating and cooling curves for Japanese kaolinite, to 1400°C.—A differential method was used with quartz sand as the comparison substance. In addition to the known reactions: (1) an endothermic from 450° to 700°, and (2) an exothermic near 950°, (3) an exothermic change between 1200° and 1300° was discovered, and it was observed that the endothermic reaction seems to include two periods of heat absorption, (1a) 450° to 650° and (1b) 650° to 700°. In explanation, the author suggests that 1a is due to dehydration, 1b to dissociation of kaolinite into free alumina and free silica, 2 to a polymerization of the alumia and 3 to the formation of amorphous sillimanite. In the discussion, E. W. Washburn calls attention to the fact that the author has neglected the endothermic reaction of quartz at 575 °C and suggests that some of his conclusions are therefore erroneous. Heating and cooling curves for alumina obtained from the nitrate, hydroxide and sulfate by calcination are given in figure 6. Exothermic reactions which are ascribed by the author to polymerization of alumia occur at 800° to 900° and at 1100° to 1200° instead of at 950° and at 1250° as in the case of kaolinite.
doi: 10.1111/j.1151-2916.1921.tb17332.xpmid: N/A
ABSTRACT Effect on electrical porcelain of the replacement of free silica by alumina and zirconia.—Since it had been suggested that free silica may be detrimental to the mechanical and the dielectric strengths of electrical porcelain, a series of sixteen batches was prepared in which various proportions of the free silica were replaced, weight for weight, by alumina, zirconia or combinations of both, and bars and disks, after burning at cone 8 l/2 to 9 or at cone 12, were tested for shrinkage, transverse strength, impact strength, heat resistance, absorption of moisture and dye penetration. The results show that resistance to sudden temperature changes can be greatly improved by substituting zirconia,—that the danger of overburning can be greatly decreased by substituting alumina and that the mechanical strengths can be increased by substituting either or both; but in the case of dielectric strength, no improvement was obtained by substituting for the free silica.
Howe, Raymond M.; Sheppard, Mark
doi: 10.1111/j.1151-2916.1921.tb17333.xpmid: N/A
ABSTRACT Influence of the alumina‐silica ratio on properties of fire‐brick.—Five experimental batches of fire‐brick were made by mixing various proportions of ganister, flint clay and plastic clay in such a way as to vary the silica content from 53 to 77 per cent and the alumina content from 43 to 20 per cent. (1) The fusion points were found only slightly lower than those of corresponding pure silica‐alumina mixtures. (2) Load tests at high temperature showed that the behavior under compression does not depend on chemical composition so much as on other factors such as the temperature of burning. (3) The resistance to spalling, as tested by alternate heating and dipping in cold water, was found to decrease as the temperature of burning was increased from 1300° to 1400 °C. The higher silica bricks were relatively more resistant at the lower temperature but not so at 1400 °C. Therefore the substitution of ganister for flint clay increases the resistance to spalling at moderate operating temperatures but is of no advantage at 1400° or above.
doi: 10.1111/j.1151-2916.1921.tb17334.xpmid: N/A
ABSTRACT Application of the drum and cable in a brick plant, for plowing and scraping the shale, for transferring it to the driers and out again and for carrying the burned bricks to the freight cars are described. The devices are simple and cheap, but they have effected a great saving and have made it much easier to get the necessary labor.
doi: 10.1111/j.1151-2916.1921.tb17335.xpmid: N/A
ABSTRACT Simple method of determining the relative expansibilities of two glasses.—Place two rods of glass side by side with the ends flush, heat these ends, weld together by pinching with forceps and then pull out a thread or thin strip with the two glasses forming opposite sides. When cool the thread will bend toward the glass having the higher total expansion up to the softening point of the softer glass. This test may be used for quantitative determination of coefficieots of expansion if a series of glasses of known expansibilities are available for comparison. The method is of particular value for investigating the welding properties of glasses, for whether or not two glasses can safely be welded together may be determined directly from the amount of curvature of the thread.
doi: 10.1111/j.1151-2916.1921.tb17336.xpmid: N/A
ABSTRACT Design and operation of glass house producer‐gas furnaces.—After discussing the proper design of checker chambers, two inefficient designs are criticised. The gases being cooled should move downward and the gases being heated should move upward, and the dimensions should be based on actual working data. The location of the ports is important and heat insulation should be carefully considered. The reversing valve should be efficient and operated regularly; and the performance of the furnace should be constantly watched with the help of instruments such as draft recorders and thermocouples, and the waste gases should be analyzed frequently. With care in design and operation it should be possible to approach the performance of a certain furnace which gave 3 lbs. of glass for each pound of coal burned.
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